Forming laterally structured heterojunction with FAPbI3 film for improving performance of MAPbBr3 photodetectors

MAPbBr3 single crystal is coated with FAPbI3 film through the half-cladding method, which forms the laterally structured heterojunction. In comparison with pure MAPbBr3 single crystal, the optoelectronic properties of the heterojunction exhibit a rare dual narrowband detection characteristic located at excitonic absorption of respective MAPbBr3 and FAPbI3 due to the different penetration depth of light photodetection. In addition, as the applied bias voltage decreases, the charge collection efficiency at the shorter wavelength range also decreases. The self-power characteristics of the device can be attributed to the existence of the built-in electric field in the heterojunction, achieving a detectivity of 5.38 × 1012 Jones for red light at 0 V. And the fast response time without an external electric field is 6.6 × 10−2 s, which is much shorter than the reported MAPbI3/MAPbBr3 heterojunction photodetector. Our results pave the way for the simple synthesis of MAPbBr3/FAPbI3 heterojunction and their applications in photodiode and a high-performance photodetector with a fast response.